1. Field of the Invention
The present invention relates to an improved dental treatment chair assembly with a treatment chair for keeping a patient in sitting position or in supine position.
2. Description of the Prior Art
The applicant of the present invention has proposed a dental treatment chair assembly with a treatment chair (bed) for keeping a patient in sitting position or in supine position as disclosed in JP-A-9-220263 and its basic structure is shown in FIG. 4.
The dental treatment chair assembly is characterized by a treatment chair 21 for holding a patient K in sitting position or in supine position.
The treatment chair 21 as shown in FIG. 4(a) comprises a headrest 21a for holding the head of a patient K, a backrest 21b for holding the back and the waist of the patient K, and a footrest 21g for holding the legs of the patient K. The above each part is connected each other so as to form a gentle curve plane. The headrest 21a is rotatably connected to the backrest 21b by means of a shaft 21c, while other parts are designed to maintain flat so as to lie the patient K on his back.
The headrest 21a is provided for holding a head of the patient K and the backrest 21b for holding a back of the patient K and they are usually formed as such shapes lacking the parts indicated by shaded portions as shown in the figure along with the shape of the object to be held on. However according to the treatment chair 21 so constructed, a projecting part 21e is provided in an estrangement (shaded portions) formed between the headrest 21a and the backrest 21b. 
Therefore, according to the above construction, for even such a patient K with long hair, it is surely prevented that his long hair hangs down from the headrest 21a. 
While the treatment chair 21 is provided with an incline means 21f with an incline control means 21fa for inclinably holding the headrest 21a against the backrest 21b as shown in FIG. 4(b) and FIG. 4(c), according to which, an oral cavity of the patient K can be set in desirable position as well as in its opening condition each corresponding to medical object, and in any conditions, the above projecting part 21e had been designed to prevent the long hair of the patient from hanging down.
The above projecting part is applied to such treatment chair capable of keeping a patient sitting or semi-supine position that the backrest is correspondingly divided into a back part and a waist part, and each corresponding part of the back part and the waist part is designed inclinable, further the footrest is also inclinable against the waist part of the backrest.
In a related art on dental treatment chair assemblies with treatment chairs, in addition to the above projecting portion, such as a dental hand piece with tubes is provided for facilitating operator""s usage at the side of a shoulder part of the backrest 21b which holds a shoulder of the patient K so that it can be pulled in and out on use. However, in the above structure, its structure would become complicated due to incorporation of a mechanism for pulling in and out tubes into the backrest 21b. 
In JP-A-59-139256, another related art is also disclosed wherein a dental treatment instrument with tubes is connected to connection ports provided around a part where a patient""s hand is positioned at a lower side of a seat of a dental treatment chair. However according to such related art, as the connection ports are provided apart from an object, namely the oral cavity of the patient, tubes of the instrument would become longer and cause difficulty in their handling.
The present invention has been proposed considering the above-mentioned problems.
Accordingly it is an object of the invention is to provide a dental treatment chair assembly in which spaces of the back or the side of the headrest as well as spaces of their around, which are closest to the oral cavity of a patient, are effectively utilized and kinds of treatment instruments capable of more convenient using for an operator can be increased without striking terror into a patient""s heart due to not using a complicated mechanism for pulling in or out the tubes.
In order to achieve the above object, the present invention is provide a dental treatment chair assembly with a treatment chair (bed) for keeping a patient in sitting position or in supine position, comprising; a treatment chair having a headrest for holding the head of a patient and a backrest for holding the back and the waist of said patient, and instrument connection ports detachably connected to a dental treatment instrument, said ports being disposed at the back or the side of said headrest, or at the back or the side of said backrest near by said headrest.
According to the dental treatment chair assembly of the present invention, estrangement or spaces which haven""t been conventionally utilized are effectively utilized.
Also, according to the present invention, since an extra instruments connection ports to which instruments are connected, are provided at the nearest position to the oral cavity of a patient, where the patient can""t see, the operator can connect the necessary instrument to the above extra instruments connection ports and give the patient necessary medical treatment without giving any terror into his heart under the circumstances easy for handling it and with a little stress on use and further an additional advantage that the length of tube provided in the treatment chair assembly can be made shorten is provided.
Further according to the present invention, a projecting part turning above which is formed so as to compensate an estrangement or a space between the headrest and the backrest functions a border partition between a space to receive treatment on a patient side and a space to give treatment on a doctor in addition by which the hair of a patient who is under the medical treatment on the treatment chair can be effectively prevented from hanging down from the treatment chair.